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PubMed2000

Schizophrenia and the mechanisms of conscious integration.

This article considers the possibility that defective interactions among distributed brain areas may underlie certain dysfunctions of conscious integration such as those seen in schizophrenia. Recent experimental evidence obtained using whole-head magnetoencephalography during binocular rivalry is first reviewed. The results outline a cortical network that underlies conscious integration in the normal brain. This network is not localized to a small part of the brain but it is distributed over frontal, parietal, temporal, and occipital areas. Large-scale simulations of the dynamics of thalamocortical integration are then examined. These studies indicate that several factors can affect the rapid integration of the activity of distributed thalamocortical regions and the resulting behavioral performance. These simulations show that an altered dynamics of corticothalamic and corticocortical re-entrant circuits can result from increased conduction delays, blockade of voltage-dependent connections, reduced synaptic density, and disruptions of the local connectivity within a single cortical area. It can also result from alterations in the activity of diffuse ascending systems that lead to defective reinforcement of integrated activity patterns. Finally, the article briefly reviews theoretical measures of the integration of multiple brain areas, such as measures of functional clustering. These measures have been applied to PET data obtained from schizophrenic subjects and controls while performing cognitive tasks. The results show a change in the functional interactions among distributed brain areas in schizophrenics despite the absence of a change in activation patterns. The possibility is raised that disruption of re-entrant interactions among cortical areas may contribute to the pathophysiology of schizophrenia.

Brain↗
PubMed2005

Electrophysiological and neuropsychological analysis of a delirious state: the role of the anterior cingulate gyrus.

Functional neuroimaging studies in humans have provided evidence that a frontal network including the anterior cingulate cortex (ACC) plays an important role in attention and awareness. Disturbed attention and awareness are core symptoms of delirium, but imaging studies of attentional dysfunctions in delirium are lacking. However, an increase of slow electroencephalographic (EEG) activity (delta, theta) is a consistent biological finding in delirium. The question whether this slow activity is related to a disturbance in the frontal attentional network has not yet been addressed. The delirium after electroconvulsive therapy (ECT) has been investigated using 32-channel resting EEG before and shortly after ECT in 12 patients with major depressive disorder. During delirium compared with baseline studies, substantial increases of delta and theta power and a decrease of alpha power were observed. The decrease of theta activity at the Fz electrode position in the following 24 h was significantly related to the recovery of awareness and performance of free recall. Source analysis with Low Resolution Electromagnetic Tomography (LORETA) indicated that the main generators of the theta excess during delirium were significantly localized in the anterior cingulate cortex, and additionally in right fronto-temporal brain areas. The results support the concept that a disturbance of attention and awareness during delirium is related to a dysfunction of an attentional network involving the ACC. However, the localization of the theta excess may reflect some motor dysfunctions as well. This dysfunction of the ACC was shown for the first time in patients during a delirious state and may represent an important pathophysiological aspect of delirium.

Attention↗
PubMed2001

Neural dynamics of motion integration and segmentation within and across apertures.

A neural model is developed of how motion integration and segmentation processes, both within and across apertures, compute global motion percepts. Figure-ground properties, such as occlusion, influence which motion signals determine the percept. For visible apertures, a line's terminators do not specify true line motion. For invisible apertures, a line's intrinsic terminators create veridical feature-tracking signals. Sparse feature-tracking signals can be amplified before they propagate across position and are integrated with ambiguous motion signals within line interiors. This integration process determines the global percept. It is the result of several processing stages: directional transient cells respond to image transients and input to a directional short-range filter that selectively boosts feature-tracking signals with the help of competitive signals. Then, a long-range filter inputs to directional cells that pool signals over multiple orientations, opposite contrast polarities, and depths. This all happens no later than cortical area MT. The directional cells activate a directional grouping network, proposed to occur within cortical area MST, within which directions compete to determine a local winner. Enhanced feature-tracking signals typically win over ambiguous motion signals. Model MST cells that encode the winning direction feed back to model MT cells, where they boost directionally consistent cell activities and suppress inconsistent activities over the spatial region to which they project. This feedback accomplishes directional and depthful motion capture within that region. Model simulations include the barberpole illusion, motion capture, the spotted barberpole, the triple barberpole, the occluded translating square illusion, motion transparency and the chopsticks illusion. Qualitative explanations of illusory contours from translating terminators and plaid adaptation are also given.

Computer Simulation↗
PubMed2002

Emotions, behaviours and mood changes in stroke.

The brain mediates and integrates all cognitive activities, emotional experiences and finally behaviours. Stroke is undoubtedly a privileged disease for human behavioural studies, because of its high incidence. Recent advances in high-resolution magnetic resonance imaging techniques and functional neuroimaging allow both the precise localization of lesions and on-line visualization of the activity of cerebral areas and networks. Nevertheless, the neuropsychiatry of stroke remains uncertain in its relationship with brain dysfunction. Clinical studies on registry populations, single case studies, and functional neuroimaging data provide interesting findings, but differences in methods and great individual intervariability still prevent a complete understanding of emotional perception and behavioural responses in stroke. We adopted an anatomical-functional model as an operational framework in order to systematize the recent literature on emotional, behavioural and mood changes after stroke. The dysfunction of the areas subserving fundamental and executive functions induces behavioural and affective changes (such as depression, anxiety, apathy) that reflect the dysfunction of the whole system. Conversely, lesions in the system of instrumental functions induce signature syndromes (aphasia, anosognosia). At any delay from stroke, the diagnosis and treatment of mood and behavioural changes are a priority for clinicians and healthcare professionals to improve the quality of life of patients.

Behavior↗
PubMed2005

Managing health inequalities locally: a baseline survey of primary care trusts' experience with health equity audit in the implementation year.

Health equity audit (HEA), a pragmatic policy tool to ensure that services and resources are focused on issues that have the highest impact on health inequalities, has now become embedded in the national strategy to tackle these inequalities through a new mandatory requirement that primary care trusts (PCTs) conduct one such audit annually. This study aimed to assess their experience through a national baseline survey in 2004, all PCTs (n = 303) being electronically mailed a questionnaire with non-respondent follow-up. Replies were received from 132 PCTs (44%), a representative sample of PCT diversity, most of whom had completed only a few steps in the audit cycle. Audit topics (most frequently coronary heart disease, smoking cessation, and access issues) and dimensions of inequity (mainly area and deprivation) were agreed through only limited engagement with local strategic partnerships. Local public health networks and multiagency teams were infrequent partners in undertaking the HEA. Most PCTs wanted comparator data, good practice examples, and specific methodological expertise. While significant progress has been made, this survey shows only limited use of HEA as a tool for multisectoral use by PCTs in partnership with others and a focus on intra-PCT comparisons at the expense of those with a wider pool of 'look-a-likes'.

Data Collection↗
PubMed2006

Lung toxicity of ambient particulate matter from southeastern U.S. sites with different contributing sources: relationships between composition and effects.

BACKGROUND: Exposure to air pollution and, more specifically, particulate matter (PM) is associated with adverse health effects. However, the specific PM characteristics responsible for biological effects have not been defined. OBJECTIVES: In this project we examined the composition, sources, and relative toxicity of samples of PM with aerodynamic diameter </= 2.5 microm (PM2.5) collected from sites within the Southeastern Aerosol Research and Characterization (SEARCH) air monitoring network during two seasons. These sites represent four areas with differing sources of PM2.5, including local urban versus regional sources, urban areas with different contributions of transportation and industrial sources, and a site influenced by Gulf of Mexico weather patterns. METHODS: We collected samples from each site during the winter and summer of 2004 for toxicity testing and for chemical analysis and chemical mass balance-based source apportionment. We also collected PM2.5 downwind of a series of prescribed forest burns. We assessed the toxicity of the samples by instillation into rat lungs and assessed general toxicity, acute cytotoxicity, and inflammation. Statistical dose-response modeling techniques were used to rank the relative toxicity and compare the seasonal differences at each site. Projection-to-latent-surfaces (PLS) techniques examined the relationships among sources, chemical composition, and toxicologic end points. RESULTS AND CONCLUSIONS: Urban sites with high contributions from vehicles and industry were most toxic.

Air Movements↗
PubMed1983

[Geographic and helicoid choroidopathies. Clinical and angiographic study; attempted classification].

Among the helicoid and geographic (or serpiginous) choroidopathies, several entities can be distinguished which differ in their clinical evolution, morphology, angiographic appearance and pathophysiology. The entity is a chorioretinal heredodystrophy characterized by tonguelike strips of choroidal atrophy radiating starlike, from the optic disc. The evolution lasts many years (up to 20 or more), with slow progression and no inflammatory stages. Other types originate from occlusion of one or several short ciliary vessels, or at least of the corresponding choriocapillary network. Inflammation is always present initially. In the acute stage, there are localized or lobular areas of exudation. After an evolution of variable duration, up to 4-5 years, exudation is followed by atrophy and formation of scars at times helicoidal in configuration but somewhat more irregular than the dystrophic entity. Similar scars around the optic disc or in the posterior pole sometimes arise from a generalized vasculopathy e.g. a giant cell arteritis. Several typical cases are presented to demonstrate the variety of manifestations that constitute tentative system of classification.

Adult↗
PubMed1996

[The architectonics of the lymphatic networks in the sheep heart].

Lymphatic networks of the heart were studied in sheep. Principal scheme of lymphatic networks structural organization in endocardium, myocardium and epicardium of the mammals studied was established to have a series of regularities similar to those in man and animals although possessing specific peculiarities. Lymphomicrocirculatory bed of the heart is composed of interdependent lymphatic networks of endocardium, myocardium and epicardium. Endocardial and epicardial lymphatic networks are plane and single-layered, while myocardial one is spatial. All heart coats lymphatic networks are characterized with local peculiarities (different loop parameters, capillary diameter and density in some areas) which indicates varying drainage and state of metabolism in different heart region.

Aging↗
PubMed1995

Creating a computer-aided intellectual environment for a consultative center of intensive care.

A consultative centre for intensive pediatrics (cip) is a center for rendering aid to children in urgent conditions who are hundreds kilometers from specialized help. Such aid is typically rendered by: 1)moving the patient to the another hospital, 2) the specialized team going out by plane, or 3) consulting the local physician by phone. The complexities of the cip dispatcher-consultation of the local physician entail a real-time system that provides a consultant with simultaneous operation with a computer and a local doctor over a phone. In 1987, a computer program, DINAR-1, was used. The core of this program was the scale of a patient's state severity "FHD-5.4" and essential elements of informative services: both a reference subsystem and one accumulating and analyzing data about cip activities, treated patients, and faults in the system of medical care. Two years of DINAR-usage showed the necessity of strengthening the decision support system for cip consultant. In 1989, a new program variant, DINAR-2, was completed. During the new variant's creation, we developed a model of decision making under conditions of information distortion (e.G., as a result of the subconscious influence of diagnostical hypotheses). This model was necessary for DINAR-2, because the most part of all information for decision making had subjective issue. Distinctions between levels of medical aid at the spot (in local hospitals) demanded the special assessment of a patient's state severity in order to adequately choose between tactical activities of the CIP. The severity of a patient's state original index depended on necessary therapy type; volume was developed. Special methodological interaction expedients between the user and the decision making system were verified in DINAR-2. The following improvements were also developed: subsystem of tuning on a definite area (1990); block of analytical final instructions on a patient's treatment (1991); visualization of introduced information (1991); determination of factors causing aggravation of a patient state (1992); and specialized subsystem of consultation of neonatals (1993). During the work, CIP got a new important function. CIP became a methodical center of the medical children aid. In keeping with this, a collection and analysis of information for regional health ministry became important part of DINAR-2. It is especially connected with touched discovery and analysis of medical defects. A system of child's death-rate analysis was especially created to make impartial decisions (1990). Expert subsystems had also an original continuation. This subsystem became a basis of the new system DINAR-created for the common pediatric physician who is attending a severely ill child. A principle addition to this system is a more complicated method of tactic solution choice. The technology of CIP supported by DINAR-systems had been bought by 35 different regions of the former USSR by 1994 (1989: one region; 1990: 2; 1991: 5; 1992: 10; 1993: 17 regions). The total population of all these regions is more than 59,000,000 people, and the total area is more than 11 million square kilometers. The main direction of DINAR's development is the creation of a regional computer network, allowing DINAR-to communicate with DINAR-in local hospitals. The first place for the usage of such a network is going to be the Big Urals Region. Big Ural consists of eight states. The total population of this territory is 28 million people and total area is 3.1 million square km. Computer networks will link eight regional CIPs to one another and the medical analytical center. The CIPs will have to be connected with 259 local hospitals. At present, the DINAR-2-CIP is installed in six states of the Big Ural, and DINAR-H is installed in four hospitals of the Sverdlovsk state.

Child↗
PubMed2000

Regional and cellular localization of the neuroendocrine prohormone convertases PC1 and PC2 in the rat central nervous system.

PC1 and PC2 are two major enzymes involved in the processing of protein precursors directed to the regulated secretory pathway. Whereas transcripts encoding both enzymes are widely distributed in the central nervous system, information regarding the localization of proteins themselves is still lacking. In an attempt to gain insight into the neurobiologic roles of PC1 and PC2, both enzymes were immunolocalized in the rat brain by using C-terminally directed antibodies, which respectively recognize the 87-kDa PC1 and the 75 and 68-kDa PC2 forms. Adjacent sections immunoreacted with PC1 or PC2 antibodies exhibited selective patterns of immunostaining in regions well characterized with respect to their biosynthesis of multiple neuropeptides such as the cerebral cortex, hippocampus, and hypothalamus. PC1 signal intensity was generally weaker than that of PC2, although both enzymes displayed extensive overlapping patterns of expression. As assessed by double-labeling experiments at the cellular level, PC1 and PC2 immunoreactive signals were localized within the trans-Golgi network and nerve terminals, in keeping with the biosynthetic pathways of neuropeptides. Immunoreactive fibers were detected in many areas throughout the brain but were particularly densely distributed in the hypothalamus and the brainstem. Both enzymes were also localized within dendrites of numerous neurons, supporting the hypothesis that dendritic neuropeptide maturation and release may occur in a large number of brain regions. Taken together, our results provide new evidence that both convertases are efficiently targeted to the neuronal regulated secretory pathway and are well poised to process protein precursors in biologically active end-products within the mammalian brain.

Animals↗
PubMed1997

Network memory.

Our thinking on the cortical organization of primate memory is undergoing a copernican change, from a neuropsychology that localizes different memories in different areas to one that views memory as a distributed property of cortical systems. We are shifting our focus from 'systems of memory' to the memory of systems. The same cortical systems that serve us to perceive and move in the world serve us to remember it. Our memories are networks of interconnected cortical neurons, formed by association, that contain our experiences in their connectional structure. Perceptual and motor memory networks are hierarchically organized in post-rolandic and pre-rolandic neocortex, respectively. Recall, recognition and working memory consist largely in their reactivation, also by association.

Animals↗
PubMed2005

Efficacy of a biomonitoring (moss bag) technique for determining element deposition trends on a mid-range (375 km) scale.

National networks detect multi-state trends in element deposition using direct measurement methods. Biomonitoring techniques have been used to examine deposition in local areas and around point sources. We sought to determine the efficacy of a moss bag technique to detect element deposition trends on a mid-range (state) scale, and to compare these results with those of the National Acid Deposition Program/National Trends Network (NADP/NTN, 1999). We sampled heavy metals, sulfur, and nitrogen deposition (21 elements) using mesh bags containing Sphagnum russowii at nine sites, over a 375 km transect crossing southern Wisconsin (upper Midwest, USA). We found statistically significant trends of decreasing deposition in a northwesterly direction for 13 elements: Al, B, Ca, Cd, Co, Cu, Cr, Fe, Mg, Mn, Ni, S, and Zn. Six of these have moderate to large changes in concentration (14-37%). The trends for Ca, Mg, and S are consistent with regional deposition patterns in 1998 isopleth maps from the NADP/NTN (1999) which are derived from a sampling array far less dense than the transect sites. This national network indicates that Ca and Mg increase to the southeast, beyond Wisconsin borders. The fact that the present study demonstrates strong correlations between both of these elements (Ca and Mg) and Al, B, Cr, Cu, Fe, Mn, Ni, and Zn (mean r for all correlations = 0.75, p < 0.02) implies that these correlated elements also increase to the southeast in neighboring states.

Environmental Monitoring↗
PubMed1991

Cellular and molecular mechanisms of cytokine networking.

A number of scientific investigations support the theory that the coordinate expression of cytokines are paramount to the successful initiation and maintenance of inflammation. Interleukin-1 and TNF appear particularly important in that these cytokines are important as both proximal and distal mediators of disease. The importance of IL-1 and TNF during early inflammatory events are exemplified via their ability to upregulate the expression of adherence proteins on the endothelium and allow inflammatory cells to bind to a localized area. In addition, these same cytokines can induce the expression of specific chemotactic cytokines from non-immune cells by a cascade effect known as cytokine networking. This interaction essentially transforms a bystander or target cell of the inflammatory response into an effector cell. Once the appropriate inflammatory cell has arrived at an inflammatory site, cytokines continue to be expressed and exert their influence by organizing the local immune response. Finally, the appropriate endogenous suppressive factors are expressed that initiate the resolution process. Thus, cytokines are effective transmitters of intracellular information that is crucial to each phase of an inflammatory reaction.

Animals↗
PubMed2003

Localization and macrostructure of subuterine lymphatic vessel networks in the bovine uterine broad ligament.

Localization and morphological features of lymphatic vessels leaving tissues of uterine horns and running through the broad ligament area were studied in mature cows after filling the lumen of the each lymphangion with varicoloured masses, mainly Microfil. The study has revealed that each branch of the lymphatic vessels emerged from both sides of the uterus and then formed double-layered networks, dorsal and ventral in the area of the mesometrium. The lymphatic branches under the uterus are very numerous and consist of enlarged precollector lymphangions. At the level of the ovary, the branches of vessels in both layers interweave each other forming the common pathway suggesting that lymph leaving the bovine uterus can be mixed in branches which are formed by elongated lymphangions running to lymphatic nodes.

Animals↗
PubMed2003

Matching marine reserve design to reserve objectives.

Recent interest in using marine reserves for marine resource management and conservation has largely been driven by the hope that reserves might counteract declines in fish populations and protect the biodiversity of the seas. However, the creation of reserves has led to dissension from some interested groups, such as fishermen, who fear that reserves will do more harm than good. These perceived differences in the effect of marine reserves on various stakeholder interests has led to a contentious debate over their merit. We argue here that recent findings in marine ecology suggest that this debate is largely unnecessary, and that a single general design of a network of reserves of moderate size and variable spacing can meet the needs and goals of most stakeholders interested in marine resources. Given the high fecundity of most marine organisms and recent evidence for limited distance of larval dispersal, it is likely that reserves can both maintain their own biodiversity and service nearby non-reserve areas. In particular, spillover of larger organisms and dispersal of larvae to areas outside reserves can lead to reserves sustaining or even increasing local fisheries. Ultimately, the success of any reserve network requires attention to the uncertainty and variability in dispersal patterns of marine organisms, clear statements of goals by all stakeholder groups and proper evaluation of reserve performance.

Conservation of Natural Resources↗
PubMed1975

Effect of local negative pressure on reproductive function.

Local negative pressure acting in the region of projection of the internal reproductive organs in rats widened and enlarged the network of blood vessels, thereby increasing the specific area of transcapillary exchange. Activation of ovulation was observed and the number of follicles and the number of young rats in the litter were increased. Local negative pressure had a positive action on the developing embryo, fetus, and newborn animal.

Animals↗
PubMed2004

Contribution of inhibitory mechanisms to direction selectivity and response normalization in macaque middle temporal area.

Inhibitory mechanisms contribute to directional tuning in primary visual cortex, and it has been suggested that, in the primate brain, the middle temporal area (MT) inherits most of its directional information from primary visual cortex (V1). To test the validity of this hierarchical scheme, we investigated whether directional tuning in MT was present upon blockade of local gamma-aminobutyratergic (GABAergic) inhibitory mechanisms. Direction selectivity during the initial 50 ms after response onset was abolished in many MT cells when the local inhibitory network was inactivated whereas direction selectivity in later response periods was largely unaffected. Thus, direction selectivity during early response periods is often generated autonomously within MT whereas direction selectivity during later response periods is either inherited from other visual areas or locally mediated by mechanisms other than gamma-aminobutyric acid type A receptor (GABA(A)) inhibition. GABAergic inhibition may also mediate contrast normalization. Our data suggest that GABA(A) inhibition implements a local direction-selective static nonlinearity, rather than a full normalization in MT. These findings put constraints on strict hierarchical models according to which MT performs more complex computations based on local motion measurements provided by earlier areas, arguing for more distributed and independent information processing.

Animals↗
PubMed2002

Early endosomes, late endosomes, and lysosomes display distinct partitioning strategies of inheritance with similarities to Golgi-derived membranes.

The pattern of inheritance of compartments of the endocytic pathway has been rarely reported, and the precise mechanism(s) are yet to be elucidated. We used antibodies reactive to early endosomes (anti-EEA1), late endosomes (anti-LBPA and anti-LAMP-1), lysosomes (anti-LAMP-1) and trans-Golgi network (TGN) (anti-GOLGA4) to examine the inheritance of these compartments in fixed human HEp-2 cells. Prior to entering M phase, these compartments display a perinuclear bias in their cytoplasmic distribution with areas of local accumulation juxtaposed to the centrosome. The location of these compartments during mitosis was examined relative to each other, the chromosomes, centrosomes and the microtubule network. During M phase early endosomes and TGN-derived compartments share overlapping subcellular distributions. A portion of these compartments display discernible clustering around the separated and migrating centrosomes in prophase. At metaphase these compartments co-localise with the mitotic spindle, are absent at the metaphase plate and do not overlay the astral microtubules. At anaphase these compartments are concentrated between shortening kinetochore microtubules and centrosomes. In addition, they appear distributed over the elongating polar microtubules in the body of the cell. From telophase and into cytokinesis these compartments concentrate around the minus ends of the constricted remnants of polar spindle microtubules and re-establish a prominent presence juxtaposed to the centrosome. In contrast, there is little evidence of movement of late endosomes and lysosomes with migrating centrosomes in prophase, and these compartments are excluded from the mitotic spindle at metaphase. However, by the end of telophase, the subcellular distribution of a portion of late endosomes and lysosomes share overlapping distributions with that of early endosomes. We conclude a portion of endosomal compartments and Golgi-derived membranes undergo ordered partitioning based on the centrosome and mitotic spindle.

Animals↗